This present application relates to tip shroud configurations for rotor blades in gas turbine engines. More specifically, but not by way of limitation, the present application relates to the design and configuration of seal rails on rotor blade tip shrouds.
Generally, combustion or gas turbine engines (hereinafter “gas turbines”) include compressor and turbine sections in which rows of blades are axially stacked in stages. Each stage typically includes a row of circumferentially-spaced stator blades, which are fixed, and a row of rotor blades, which rotate about a central turbine axis or shaft. In operation, generally, the compressor rotor blades are rotated about the shaft, and, acting in concert with the stator blades, compress a flow of air. This supply of compressed air then is used within a combustor to combust a supply of fuel. The resulting flow of hot expanding combustion gases, which is often referred to as working fluid, is then expanded through the turbine section of the engine. Within the turbine, the working fluid is redirected by the stator blades onto the rotor blades so to power rotation. The rotor blades are connected to a central shaft such that the rotation of the rotor blades rotates the shaft. In this manner, the energy contained in the fuel is converted into the mechanical energy of the rotating shaft, which, for example, may be used to rotate the rotor blades of the compressor, so to produce the supply of compressed air needed for combustion, as well as, for example, rotate the coils of a generator so to generate electrical power. During operation, because of the temperatures of the hot-gas path, the velocity of the working fluid, and the rotational velocity of the engine, the rotor blades within the turbine become particularly stressed with extreme mechanical and thermal loads.
Many industrial applications, such as those involving power generation and aviation, still rely heavily on gas turbines, and because of this, the engineering of more efficient engines remains an ongoing and important objective. As will be appreciated, even incremental advances in machine performance, efficiency, or cost-effectiveness are meaningful in the highly competitive markets that have evolved around this technology. While there are several known strategies for improving the efficiency of gas turbines, such as, for example, increasing the size of the engine, firing temperatures, or rotational velocities, each of these generally places additional strain on those already highly stressed hot-gas path components. As a result, there remains a need for improved apparatus, methods or systems that alleviate such operational stresses or, alternatively, that enhance the durability of such components so they may better withstand them.
As will be appreciated, this need is particularly evident in regard to turbine rotor blades, where marketplace competitiveness is exceedingly high and the many design considerations are highly complex and often competing. As such, novel rotor blade designs, such as those presented herein, that succeed in balancing these considerations in ways that optimize or enhance one or more desired performance criteria—while still adequately promoting structural robustness, part-life longevity, cost-effective engine operation, and/or the efficient usage of coolant—represent technological advances having considerable value.